JP2016152204A - Solid-state battery and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state battery of high stability, capable of exhibiting excellent battery characteristics.SOLUTION: A solid-state battery 1 includes a negative electrode layer 9 containing a negative electrode active material, a positive electrode layer 5 containing a positive electrode active material, and a solid electrolyte layer 7 provided between the negative electrode layer 9 and positive electrode layer 5 so as to come into contact therewith. Following relation is satisfied ((Vp-V)/Vp×100)≤3%, where Vp is the total volume of the negative electrode layer 9, positive electrode layer 5 and solid electrolyte layer 7, and Vis the total volume of the negative electrode layer 9, positive electrode layer 5 and solid electrolyte layer 7 when compressed with a static pressure of 980 MPa.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to a solid state battery and a method for manufacturing the same.

  In recent years, due to industrial demands, development of batteries with high energy density and high safety has been actively conducted. For example, lithium ion secondary batteries are put into practical use not only in the fields of information-related equipment and communication equipment, but also in the automobile field. In the automobile field, safety is particularly important because it is related to human life.

  Since the electrolyte solution containing a flammable organic solvent is used for the lithium ion secondary battery currently marketed, when a short circuit occurs, it may overheat or ignite. On the other hand, a solid battery using a solid electrolyte instead of the electrolytic solution has been proposed (see Patent Documents 1 to 3).

  According to the solid state batteries described in Patent Documents 1 to 3, by not using a flammable organic solvent, it is possible to greatly reduce the possibility of ignition or rupture even if a short circuit occurs. Therefore, in these solid batteries, there is a possibility that safety can be significantly improved as compared with a lithium ion secondary battery using an electrolytic solution.

JP 2012-104270 A International Publication WO2012 / 164723 JP 2014-120199 A

  However, in the above-described conventional solid battery, when the contact between the positive electrode layer and the solid electrolyte and the contact between the negative electrode layer and the solid electrolyte is not sufficiently maintained because the electrolyte is solid, the resistance in the battery is reduced. It becomes large and it becomes difficult to exhibit excellent battery characteristics.

  Here, in order to lower the resistance in the battery, it is conceivable to charge and discharge while applying an external pressure to the solid state battery. However, in that case, a structure for applying an external pressure is required separately, which increases the product cost and decreases the energy density of the solid state battery.

  An object of the present invention is to provide a solid battery that has high safety and can exhibit excellent battery characteristics.

The solid battery disclosed in this specification includes a negative electrode layer including a negative electrode active material, a positive electrode layer including a positive electrode active material, and the negative electrode layer and the positive electrode layer between the negative electrode layer and the positive electrode layer, respectively. A total volume of the negative electrode layer, the positive electrode layer and the solid electrolyte layer is Vp, and the total of the negative electrode layer, the positive electrode layer and the solid electrolyte layer is 980 MPa. When the volume when pressurized by hydrostatic pressure is V ₉₈₀ , {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3% holds.

  According to the solid state battery disclosed in this specification, it is possible to exhibit high safety and excellent battery characteristics.

FIG. 1 is a cross-sectional view illustrating a solid state battery according to an embodiment disclosed in the specification. FIG. 2 is a cross-sectional view showing a process of consolidating battery materials using hydrostatic pressure. FIG. 3 is a cross-sectional view showing an example in which uniaxial pressing is performed in the consolidation process of the laminated body. FIG. 4 is based on the ratio of the initial discharge capacity value when the initial discharge capacity is 100% when pressed at a hydrostatic pressure of 980 MPa and the V ₉₈₀ when pressed at a hydrostatic pressure of 980 MPa in a solid battery. It is a figure which shows the relationship with the done porosity. FIG. 5 is a diagram showing the relationship between the cell resistance and the porosity based on _V980 when pressurized with a hydrostatic pressure of 980 MPa in a solid state battery. FIG. 6 is a diagram showing the relationship between the cycle retention ratio and the porosity based on _V980 when pressurized with a hydrostatic pressure of 980 MPa in a solid state battery.

(Embodiment)
−Structure of solid state battery−
FIG. 1 is a cross-sectional view illustrating a solid state battery according to an embodiment disclosed in the present specification. The figure schematically shows the configuration of the solid state battery 1 for easy understanding, and the ratio of the thicknesses of the respective layers may be different from the example shown in FIG.

  As shown in FIG. 1, the solid battery 1 of the present embodiment includes a negative electrode current collector layer 11, a negative electrode layer 9, a solid electrolyte layer 7, a positive electrode layer 5, and a positive electrode current collector provided in order from the bottom. And a body layer 3. The solid electrolyte layer 7 provided between the negative electrode layer 9 and the positive electrode layer 5 is in direct contact with the negative electrode layer 9 and the positive electrode layer 5, respectively. The negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5 are each composed of powder and are pressure-molded. The planar shape of the solid battery 1 is not particularly limited, and may be a circle, a quadrilateral, or the like.

  The negative electrode current collector layer 11 is made of a conductor, and is made of a metal such as copper (Cu), nickel (Ni), stainless steel, or nickel-plated steel. The thickness of the negative electrode current collector layer 11 is, for example, about 10 μm to 20 μm.

  The negative electrode layer 9 contains a powdered negative electrode active material. The average particle diameter of the negative electrode active material is, for example, in the range of 5 μm to 20 μm. The content rate of the negative electrode active material in the negative electrode layer 9 is, for example, in the range of 60 wt% to 95 wt%. The negative electrode layer 9 may further include a binder that does not cause a chemical reaction with the solid electrolyte layer 7, a powdered solid electrolyte material, a conductive material, and the like.

Various known materials can be used as the negative electrode active material, and a carbon active material, a metal active material, an oxide active material, or the like can be used. Examples of the carbon active material include graphite such as artificial graphite and natural graphite, and amorphous carbon such as hard carbon and soft carbon. Examples of the metal active material include lithium (Li), indium (In), aluminum (Al), silicon (Si), and tin (Sn). Examples of the oxide active material include Nb ₂ O ₅ , Li ₄ Ti ₅ O ₁₂ , and SiO. These negative electrode active materials may be used independently and 2 or more types may be used together. Although the thickness of the negative electrode layer 9 is not specifically limited, For example, it is about 50 micrometers-300 micrometers.

The solid electrolyte layer 7 is composed of a powdery solid electrolyte. The average particle diameter of the solid electrolyte is, for example, in the range of 1 μm to 10 μm. As the solid electrolyte, for example, a sulfide-based solid electrolyte containing at least lithium (Li), phosphorus (P), and sulfur (S) can be used. An example of the sulfide-based solid electrolyte is Li ₂ S—P ₂ S ₅ . This sulfide-based solid electrolyte exhibits good lithium ion conductivity, and may contain sulfides such as SiS ₂ , GeS ₂ , B ₂ S ₃ in addition to Li ₂ S—P ₂ S ₅ . Although the thickness of the solid electrolyte layer 7 is not specifically limited, For example, it is about 10 micrometers-200 micrometers.

Further, an inorganic solid electrolyte to which Li ₃ PO ₄ , halogen, a halogen compound or the like is added may be used as the solid electrolyte.

The above-mentioned Li ₂ S—P ₂ S ₅ is obtained by heating Li ₂ S and P ₂ S ₅ to a melting temperature or higher, melting and mixing them at a predetermined ratio, holding them for a predetermined time, and then rapidly cooling them. can get. The _Li 2 _S-P 2 _{S 5,} the powder of Li ₂ S and _P 2 _{S 5} can be obtained by treating the mechanical milling method. The mixing ratio of Li ₂ S and P ₂ S ₅ is usually 50:50 to 80:20, preferably 60:40 to 75:25 in terms of molar ratio.

  The positive electrode layer 5 contains a powdered positive electrode active material. The average particle diameter of the positive electrode active material is, for example, in the range of 2 μm to 10 μm. The content rate of the positive electrode active material in the positive electrode layer 5 is, for example, in the range of 65 wt% to 95 wt%. The positive electrode layer 5 may further include a binder that does not cause a chemical reaction with the solid electrolyte layer 7, a powdered solid electrolyte material, a conductive material, and the like. Any material capable of reversibly occluding and releasing lithium ions can be used as the positive electrode active material. For example, lithium cobalt oxide (LCO), lithium nickelate, lithium nickel cobaltate, nickel cobalt lithium aluminumate (NCA), nickel cobalt lithium manganate (NCM), lithium manganate, lithium iron phosphate, sulfide Examples thereof include nickel, copper sulfide, sulfur, iron oxide, vanadium oxide and the like. These positive electrode active materials may be used independently and 2 or more types may be used together.

Of the positive electrode active materials described above, lithium salts of transition metal oxides having a layered rock salt structure are preferably used. Here, the “rock salt type structure” is a sodium chloride type structure that is one kind of crystal structure, and the face-centered cubic lattice formed by each of the cation and the anion is one of the edges of the unit cell. A structure shifted by / 2. For example, Li _1-x-yz NixCo _y Al _z O ₂ (NCA) or Li _1-x-yz NixCo _y Mn _z O ₂ (NCM) (0 <x <1, 0 <y <1, As a positive electrode active material, a lithium salt of a ternary transition metal oxide represented by 0 <z <1 and x + y + z <1) can be given.

  For example, a nonpolar resin having no polar functional group is used as the binder. Therefore, the positive electrode layer binder is inactive to highly reactive solid electrolytes, particularly sulfide-based solid electrolytes. As the positive electrode layer binder, for example, SBS (styrene butadiene block polymer), SEBS (styrene ethylene butadiene styrene block polymer), styrene-based thermoplastic elastomers such as styrene- (styrene butadiene) -styrene block polymer, SBR (styrene butadiene rubber), BR (butadiene rubber), NR (natural rubber), IR (isoprene rubber), EPDM (ethylene-propylene-diene terpolymer) and partial hydrides or complete hydrides thereof Etc. In addition, polystyrene, polyolefin, olefinic thermoplastic elastomer, polycycloolefin, silicone resin, and the like can be used as the binder. Although the thickness of the positive electrode layer 5 is not specifically limited, For example, it is about 50 micrometers-350 micrometers.

  The positive electrode current collector layer 3 is made of a conductor, for example, a metal such as aluminum (Al) or stainless steel. The thickness of the positive electrode current collector layer 3 is not particularly limited, but is, for example, about 10 μm to 20 μm.

  The planar areas of the negative electrode current collector layer 11, the negative electrode layer 9, the solid electrolyte layer 7, the positive electrode layer 5, and the positive electrode current collector layer 3 may be equal to each other as shown in FIG. The planar area of the body layer 3 is smaller than the planar areas of the negative electrode current collector layer 11, the negative electrode layer 9 and the solid electrolyte layer 7, and the planar outer shapes of the positive electrode layer 5 and the positive electrode current collector layer 3 are the negative electrode current collector layer 11. The negative electrode layer 9 and the solid electrolyte layer 7 may be provided so as to be inside the planar outer shape (see FIG. 3). By making the planar areas of the positive electrode layer 5 and the positive electrode current collector layer 3 smaller than the planar areas of the negative electrode current collector layer 11, the negative electrode layer 9, and the solid electrolyte layer 7, the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer When the pressure is applied to 5, the protrusion of the positive electrode layer 5 to the outside can be prevented, so that it is difficult to cause a short circuit.

In the solid battery 1 of the present embodiment, the total volume of the negative electrode layer 9, the positive electrode layer 5 and the solid electrolyte layer 7 is Vp, and the negative electrode layer 9, the positive electrode layer 5 and the solid electrolyte layer 7 are entirely pressurized with a hydrostatic pressure of 980 MPa. When the volume at this time is V ₉₈₀ , it is preferable that {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3% is satisfied. In the present specification, {(Vp−V ₉₈₀ ) / Vp × 100} is referred to as “a porosity based on V ₉₈₀ ”, and a general void indicating a ratio of an actual void in a substance. It may be distinguished from the rate (hereinafter referred to as “true porosity”).

When the negative electrode layer 9, the positive electrode layer 5, and the solid electrolyte layer 7 are formed using a general method for manufacturing a known lithium ion secondary battery, usually {(Vp−V ₉₈₀ ) / Vp × 100} is Greater than 3%. On the other hand, in the solid battery 1 of the present embodiment, the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5 are consolidated so that {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3%. The contact between the negative electrode active material and the solid electrolyte and the contact between the positive electrode active material and the solid electrolyte can be sufficiently ensured. For this reason, the electrical resistance between the negative electrode layer 9 and the solid electrolyte layer 7 and the electrical resistance between the positive electrode layer 5 and the solid electrolyte layer 7 can be kept small without applying external pressure during operation. As a result, the solid battery 1 of the present embodiment can exhibit excellent battery characteristics.

  Moreover, since the solid battery 1 of the present embodiment does not require a structure for applying an external pressure, the product cost can be reduced. Moreover, a high energy density can be obtained. Furthermore, since the solid battery 1 of the present embodiment is an all-solid battery, the risk of ignition and the like is extremely low as compared with a battery using a flammable organic electrolyte.

Here, the negative electrode layer 9, the positive electrode layer 5, and the solid electrolyte layer 7 are consolidated by pressurizing the whole of the negative electrode layer 9, the positive electrode layer 5, and the solid electrolyte layer 7 by hydrostatic pressure of 980 MPa or more. In this case, the volume does not decrease even when a hydrostatic pressure of 980 MPa is applied again after the solid battery 1 is manufactured, so {(Vp−V ₉₈₀ ) / Vp × 100} = 0%.

The battery characteristics can be improved by setting the porosity of the negative electrode layer 9, the positive electrode layer 5, and the solid electrolyte layer 7 to an appropriate range even if the constituent materials of the solid electrolyte layer 7 are different. This is because the contact between the solid particles is a factor that determines the characteristics of the solid battery, regardless of the constituent material of the solid electrolyte. Accordingly, even if the solid electrolyte is other than sulfide type (for example, oxide type or phosphoric acid type), if {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3% holds, It is considered that excellent battery characteristics similar to those of the solid battery 1 can be exhibited.

  Although FIG. 1 shows a monopolar solid battery 1, the solid battery 1 may be a bipolar battery. Further, the monopolar battery structure shown in FIG. 1 may be stacked a plurality of times.

  The solid battery 1 is not necessarily an all solid lithium ion secondary battery, and may be an all solid alkaline ion secondary battery (for example, an all solid sodium ion secondary battery).

  Further, the solid battery 1 of the present embodiment may be in a state of being vacuum laminated packed with a metal foil, a resin film, or the like. Even in this case, the solid battery 1 of the present embodiment can exhibit excellent battery characteristics without receiving external pressure. In the solid battery 1 of this embodiment, the pressure applied to the negative electrode layer 9, the positive electrode layer 5, and the solid electrolyte layer 7 from the outside in the atmosphere is equal to or lower than atmospheric pressure.

-Manufacturing method of solid state battery-
As an example of the manufacturing method of the solid battery 1, there is a method using coating. First, a powdery positive electrode active material, a solid electrolyte, a conductive additive, a binder, and the like are added to an appropriate solvent and mixed to prepare a coating solution for the positive electrode layer 5. Next, the coating liquid is applied to one surface of the positive electrode current collector layer 3 and dried. In this step, a nonpolar solvent having low reactivity with the sulfide-based solid electrolyte is used. For example, aromatic hydrocarbons such as xylene, toluene, and ethylbenzene, and aliphatic hydrocarbons such as pentane, hexane, and heptane can be used as the solvent.

  On the other hand, a powdery negative electrode active material, a solid electrolyte, a conductive additive, and a binder are added to and mixed with the above-described solvent to prepare a coating solution for the negative electrode layer 9. Next, the coating liquid is applied to one surface of the negative electrode current collector layer 11 and dried.

  Next, for example, a sulfide-based powdery solid electrolyte and a binder are added to a solvent and mixed to prepare a coating solution for the electrolyte layer. Next, the coating liquid is applied to the surface of the negative electrode current collector layer 11 on which the negative electrode layer material is applied, and dried.

  Next, the positive electrode current collector layer 3 and the negative electrode current collector layer 11 are each cut into appropriate sizes. Next, the negative electrode current collector is bonded so that the surface of the negative electrode current collector layer 11 coated with the electrolyte material and the surface of the positive electrode current collector layer 3 coated with the positive electrode layer material are joined. After the layer 11 and the positive electrode current collector layer 3 are overlaid, a consolidation process is performed as follows. Here, a laminate of the negative electrode current collector layer 11 and the positive electrode current collector layer is referred to as a “battery laminate”.

  FIG. 2 is a cross-sectional view showing a process of consolidating battery materials using hydrostatic pressure. As shown in the figure, after the battery laminate is disposed on the support member 13 made of a rigid plate, the battery laminate (laminate) 24 is sealed with an exterior body 14 made of metal foil or the like.

  Subsequently, the battery laminate 24 and the support member 13 are sealed with a protective body 15 made of a resin film or the like, and submerged in a pressurized medium 17 filled in a high-pressure container (not shown). In this state, the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5 are consolidated by applying a pressure 19 from above to the pressurized medium 17 in the container. According to this method, a hydrostatic pressure 21 having a desired value can be applied to the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5 from the side and from above.

  By this step, since the bonding between the negative electrode layer 9 and the solid electrolyte layer 7 and the bonding between the positive electrode layer 5 and the solid electrolyte layer 7 are sufficiently ensured, the electric resistance in the battery can be reduced. Moreover, since the density of the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5 can be increased, the current density of the solid battery 1 can be improved.

In the consolidation step, the value of the hydrostatic pressure applied from the side and the upper side to the battery laminate 24 is not particularly limited, but if it is 450 MPa or more, V ₉₈₀ in the negative electrode layer 9, the solid electrolyte layer 7, and the positive electrode layer 5. Since the porosity based on the reference can be 3% or less, it is preferable. By this method, the solid battery 1 which shows the outstanding cycle maintenance factor and initial discharge capacity is producible.

  Note that it is difficult to bring the true porosity close to 0 even if the hydrostatic pressure applied to the battery laminate is excessively increased, and the facility for applying the hydrostatic pressure becomes large. For this reason, it is more preferable that the hydrostatic pressure applied to the battery laminate is 980 MPa or less.

  In this step, since the hydrostatic pressure is applied with the support material 13 provided under the negative electrode current collector layer 11, the elastic material is provided under the negative electrode current collector layer 11 when the support material 13 is not provided. The warpage of the solid battery 1 produced can be greatly reduced as compared with the case where the battery is provided. In the consolidation step, different hydrostatic pressures can be applied to the portion of the laminate 24 that is in contact with the support member 13 and the portion that is not in contact with the support member 13.

  The support material 13 used in this step only needs to have a thickness with which sufficient rigidity can be obtained. For example, the support material 13 has a thickness of about 3 mm to 5 mm. The support material 13 should just be comprised, for example with the metal, and may be comprised with the aluminum as an example.

  After this process, the solid battery 1 of this embodiment can be produced by taking out the solid battery 1 from the pressurized medium, removing the protective body 15 and then removing the support material 13 from the solid battery 1.

  In addition, although this embodiment demonstrated the case where a hydrostatic pressure was applied to the laminated body 24, as shown in FIG. 3, you may compress the laminated body 24 by uniaxial press processing, such as a roll press and a double-sided press. . When uniaxial pressing is performed, the planar areas of the positive electrode layer 5 and the positive electrode current collector 3 are made smaller than the planar areas of the solid electrolyte layer 7, the negative electrode layer 9, and the negative electrode current collector layer 11, and the positive electrode layer 5 and the positive electrode current collector are obtained. It is preferable that the positive electrode layer 5 and the positive electrode current collector 3 are disposed so that the three-dimensional outer shape of the third electrode falls within the flat outer shapes of the solid electrolyte layer 7, the negative electrode layer 9, and the negative electrode current collector layer 11.

  According to this method, even when the laminate 24 is sandwiched in the press machine 25 and the positive electrode layer 5 spreads outward, it is effective that the positive electrode layer 5 contacts the negative electrode layer 9 and the negative electrode current collector layer 11. Can be prevented.

  In addition, the structure and manufacturing method of the solid battery 1 demonstrated above are examples of embodiment, Comprising: A structural member, a manufacturing procedure, etc. may be changed suitably.

<Example>
Next, examples of the solid state battery 1 according to the present embodiment will be described. In addition, all the operations in the following Examples and Comparative Examples were performed in a dry room having a dew point temperature of −55 ° C. or lower.
[Example 1]
-Formation of positive electrode layer-
Powdered LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (positive electrode active material) and powdered Li ₂ S—P ₂ S ₅ (sulfide-based solid electrolyte), and vapor-grown carbon fiber powder ( Conductive aid) was weighed at a mass ratio of 60: 35: 5, and then a xylene solution (solvent) in which butadiene rubber as a binder was dissolved in the mixed powder was added to the total weight of the mixed powder. Then, the binder was added so as to be 2% by mass and mixed using an auto-revolution mixer to prepare a coating solution for the positive electrode layer.

  Subsequently, the above-mentioned coating liquid was apply | coated on the 12-micrometer-thick aluminum foil (positive electrode electrical power collector) using the desktop screen printer. Thereafter, the aluminum foil coated with the coating solution was dried at 40 ° C. for 10 minutes using a hot plate, and then vacuum dried at 40 ° C. for 12 hours. This formed the positive electrode layer on the aluminum foil. The thickness of the positive electrode layer was 300 μm.

-Formation of negative electrode layer-
Next, a powdery graphite powder (negative electrode active material), Li ₂ S—P ₂ S ₅ (sulfide-based solid electrolyte), and vapor-grown carbon fiber powder (conductive aid) are in a mass ratio of 60: 35: 5. Next, a xylene solution (solvent) in which butadiene rubber as a binder was dissolved in this mixed powder was so adjusted that the binder was 3% by mass with respect to the total weight of the mixed powder. The coating liquid for negative electrode layers was produced by adding to and mixing using a rotation and revolution mixer. Subsequently, the coating liquid for negative electrode layers was apply | coated on the 10-micrometer-thick copper foil (negative electrode collector) using the desktop screen printer.

  The copper foil coated with the coating solution was dried at 40 ° C. for 10 minutes using a hot plate and then vacuum dried at 40 ° C. for 12 hours. Thereby, the negative electrode layer was formed on the copper foil. Subsequently, the copper foil (namely, negative electrode structure) in which the negative electrode layer was formed was rolled using the roll press machine whose roll gap is 50 micrometers. The total thickness of the negative electrode layer and the copper foil was about 120 μm.

-Formation of electrolyte layer-
A xylene solution (solvent) in which a binder was dissolved was added to powdered Li ₂ S—P ₂ S ₅ (sulfide-based solid electrolyte), and mixed using a rotation and revolution mixer. Thereby, the coating liquid for electrolyte layers was produced.

  Subsequently, the coating liquid for electrolyte layers was apply | coated on the negative electrode structure using the desktop screen printer. Thereafter, the negative electrode structure was dried at 40 ° C. for 10 minutes using a hot plate, and then vacuum dried at 40 ° C. for 12 hours. Thereby, a solid electrolyte layer was formed on the negative electrode structure. The thickness of the solid electrolyte layer after drying was 70 μm.

-Fabrication of solid state battery-
The negative electrode structure and the positive electrode current collector are each punched out with a Thomson blade after the sheet-like negative electrode structure on which the negative electrode structure solid electrolyte layer is formed and the sheet-like positive electrode current collector layer on which the positive electrode layer is formed. The layers were laminated so that the solid electrolyte layer and the positive electrode layer were in contact with each other. In this state, the laminate was vacuum laminated. Here, the negative electrode structure solid electrolyte layer was made to be 0.7 mm larger in the vertical and horizontal directions than the positive electrode layer.

Next, the laminate was placed on an aluminum plate (support material) having a thickness of 3 mm, and the laminate was vacuum laminated pack including the support material. The laminate was submerged in a pressurized medium as shown in FIG. 2 and subjected to a hydrostatic pressure treatment (consolidation step) at 455 MPa. Thereby, the single cell (single cell) of the solid battery 1 was produced.
[Examples 2 to 5]
Solid batteries according to Examples 2 to 5 were produced in the same manner as in Example 1 except for the consolidation step. In the consolidation step, the example in which the hydrostatic pressure was set to 490 MPa was set as Example 2, the example in which the hydrostatic pressure was set to 525 MPa was set as Example 3, the example in which the hydrostatic pressure was set to 675 MPa was set as Example 4, and the hydrostatic pressure was set to 980 MPa. An example is referred to as Example 5.
[Comparative Examples 1-6]
Solid batteries according to Comparative Examples 1 to 6 were produced in the same manner as in Example 1 except for the consolidation step. The example which does not perform a compaction process was made into the comparative example 1. Further, an example in which the hydrostatic pressure is 75 MPa is set as Comparative Example 2, an example in which the hydrostatic pressure is set to 150 MPa is set as Comparative Example 3, an example in which the hydrostatic pressure is set to 225 MPa is set as Comparative Example 4, and an example in which the hydrostatic pressure is set to 375 MPa is compared. Example 5 was adopted.

-V ₉₈₀ Measurement of porosity relative to the -
First, the total volume Vp of the negative electrode layer, the solid electrolyte layer, and the positive electrode layer in the solid battery is punched out in a size of φ13 mm, and the film thickness and weight are measured using a film thickness meter and a balance, respectively. Based on the above calculation.

Next, a laminate composed of the negative electrode current collector layer, the negative electrode layer, the solid electrolyte layer, the positive electrode layer, and the positive electrode current collector layer is placed on an aluminum plate (support material) having a thickness of 3 mm with the negative electrode current collector layer facing down. It was put on. This laminated body was submerged in a pressurized medium as shown in FIG. Next, a hydrostatic pressure of 980 MPa was applied to the laminate by applying pressure to the pressurized medium from above. Thereafter, the laminate is taken out from the vacuum laminate pack, and the total volume (V ₉₈₀ ) of the negative electrode layer, the solid electrolyte layer, and the positive electrode layer is punched out in a size of φ13 mm, and the film thickness and weight are measured respectively. And calculating using a balance.

By calculating a value of {(Vp−V ₉₈₀ ) / Vp × 100} from the measured values obtained above, a porosity based on V ₉₈₀ was obtained.

-Measurement of cycle maintenance rate-
A solid battery was placed in a 25 ° C. thermostat, and charge / discharge was performed at a current density of 0.5 mA / cm ² and between 4 V and 2.5 V. The discharge capacity at the first cycle was taken as 100%, and the ratio of the discharge capacity at the 50th cycle was calculated as the cycle retention rate.

-Cell resistance-
A solid battery was placed in a 25 ° C. thermostat, and charge / discharge was performed at a current density of 0.5 mA / cm ² and between 4 V and 2.5 V. In the charge state at the fifth cycle, impedance (cell resistance) was measured.

-Initial discharge capacity-
A solid battery was placed in a 25 ° C. thermostat, and charge / discharge was performed at a current density of 0.5 mA / cm ² and between 4 V and 2.5 V. The ratio of the initial discharge capacity was calculated when the initial discharge capacity of the solid state battery when the consolidation was performed using a hydrostatic pressure of 980 MPa (Example 5) was 100%.

-Measurement results-
Table 1 shows the measurement results of the solid batteries according to Examples 1 to 5 and Comparative Examples 1 to 6.

Also shows the relationship between the reference and the porosity of the initial discharge capacity and V ₉₈₀ in FIG. 4 shows the relationship between the reference and the porosity of the cell resistance and V ₉₈₀ in FIG. 5, the cycle retention ratio and V ₉₈₀ The relationship with the standard porosity is shown in FIG.

Table The results of Examples 1 to 5 shown in 1, when performing compaction in the above hydrostatic pressure 455MPa, it was confirmed that the porosity relative to the V ₉₈₀ is in 3%.

Further, as shown in FIG. 5, when the porosity based on V ₉₈₀ is 3% or less, it is confirmed that the cell resistance is significantly lower than that when the porosity exceeds 3%. did it. Further, as shown in FIGS. 4 and 6, in Examples 1 to 5 where the porosity based on V ₉₈₀ is 3% or less, the initial discharge capacity is larger than that of Comparative Examples 1 to 6 and 50 cycles. It was also confirmed that the discharge capacity was well maintained even after charging / discharging.

  From the results of Comparative Examples 1 to 6, it was confirmed that as the hydrostatic pressure in the consolidation treatment was decreased, the cell resistance was increased, the initial discharge capacity was decreased, and the cycle maintenance ratio was decreased.

  As described above, the solid state battery according to an example of the present disclosure can be applied to various portable devices, vehicles, and the like.

DESCRIPTION OF SYMBOLS 1 Solid battery 3 Positive electrode collector layer 5 Positive electrode layer 7 Solid electrolyte layer 9 Negative electrode layer 11 Negative electrode collector layer 13 Support material 14 Exterior body 15 Protective body 17 Pressurizing medium 19 Pressure 21 Hydrostatic pressure 24 Laminate 25 Press

Claims (7)

A negative electrode layer containing a negative electrode active material;
A positive electrode layer containing a positive electrode active material;
A solid electrolyte layer provided between the negative electrode layer and the positive electrode layer so as to be in contact with the negative electrode layer and the positive electrode layer,
The total volume of the negative electrode layer, the positive electrode layer and the solid electrolyte layer is Vp, and the volume when the whole of the negative electrode layer, the positive electrode layer and the solid electrolyte layer is pressurized at a hydrostatic pressure of 980 MPa is V ₉₈₀ . In this case, a solid battery that satisfies {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3%. The solid state battery according to claim 1,
The said negative electrode layer, the said positive electrode layer, and the said solid electrolyte layer are each comprised with the powder, and are solidified, The solid battery characterized by the above-mentioned. The solid state battery according to claim 1 or 2,
The solid electrolyte layer is constituted by a sulfide solid electrolyte containing at least lithium, phosphorus and sulfur. In the solid battery according to any one of claims 1 to 3,
A solid battery characterized in that, in the air, a pressure applied from the outside to the negative electrode layer, the positive electrode layer, and the solid electrolyte layer is equal to or lower than atmospheric pressure. A solid battery comprising a step of applying pressure to a laminate having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer provided between the negative electrode layer and the positive electrode layer to consolidate the laminate. A manufacturing method comprising:
The total volume of the negative electrode layer, the positive electrode layer, and the solid electrolyte layer after consolidation is set to Vp, and the whole of the negative electrode layer, the positive electrode layer, and the solid electrolyte layer after consolidation is pressurized at a hydrostatic pressure of 980 MPa. A solid battery manufacturing method in which {(Vp−V ₉₈₀ ) / Vp × 100} ≦ 3% holds when the volume at the time is V ₉₈₀ . In the manufacturing method of the solid battery according to claim 5,
In the step of consolidating the laminate, by applying a hydrostatic pressure to the laminate formed on a support member made of a rigid plate, the portion of the laminate that is in contact with the support member and the support member are in contact with each other. A method for producing a solid state battery, wherein different hydrostatic pressures are applied to an unexposed portion. In the manufacturing method of the solid battery according to claim 6,
In the step of compacting the laminate, a hydrostatic pressure applied to a portion of the laminate that is not in contact with the support material is 450 MPa or more.

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